Explosive-loaded ground anchor assembly

ABSTRACT

A ground anchor retaining assembly for providing a ground-retained anchor to restrain an object, such as an above ground structure, for example, a tower or pylon connected to it. The assembly is adapted to be received within a borehole within the ground and comprising an anchor shaft; a housing connected to the shaft and surrounding at least a part of the anchor shaft; the housing with the part of the shaft defining a chamber; and an effective amount of an explosive within the chamber connectable to a detonator to effect detonation of the explosive to effect deformation of the housing as to provide frictional ground retention of the housing within the ground. The assembly also may be used to provide ground anchors within the walls, roof and floors of mine shafts and tunnels.

FIELD OF THE INVENTION

This invention relates to a ground anchor, for use underground in mine shafts, tunnels and the like, or particularly, for tying down structures, such as towers, electricity pylons and the like with guy wires above ground, and, more particularly, to an assembly of said anchor comprising a portion thereof encased in an explosive-loaded housing.

BACKGROUND OF THE INVENTION

Utilities and other companies, which use guy towers, use various mechanical devices to anchor the guy wires that hold the towers vertically. Typical installations require than an anchor rod or shaft held in the ground to provide a holding power sufficient to hold the tower upright under the designed conditions of wind, ice and tower vibrations.

Typical examples of such mechanical anchors known in the art include multi-helix screws, expanding anchors, grouted anchors and wood mats.

Below ground or within mountains and the like, as in mine shafts, tunnels and the like, retained members such as rods, bolts, thick wire members, and the like, may be retained in the walls, face, roof or floor of a tunnel within a concrete-filled borehole.

Although the aforesaid prior art is in established use, there is, however, a need for a ground anchor system that provides less disturbance of the ground adjacent the resultant borehole during installation and completion of the installed resultant ground anchor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a ground anchor assembly which provides a resultant installed ground anchor that minimizes disruption of the annular sides of the borehole and maintains the integrity of the surrounding ground.

Accordingly, in its broadest aspect, the invention provides a ground anchor retaining means assembly for providing a ground-retained anchor retaining means to restrain an object connected thereto, said assembly adapted to be received within a borehole within said ground and comprising

-   -   an elongate anchor shaft;     -   a housing connected to said shaft and surrounding at least a         part of said anchor shaft;     -   said housing with said part of said shaft defining a chamber;         and     -   an effective amount of an explosive within said chamber         connectable to detonator means to effect detonation of said         explosive to effect deformation of said housing as to provide         frictional ground retention of said housing within said ground.

The invention provides in one preferred aspect, a ground anchor assembly of use in providing a ground-retained anchor for use with guy means to restrain a vertical structure, said assembly adapted to be received within a borehole within said ground and comprising

-   -   an anchor shaft;     -   a housing surrounding at least a part of said anchor shaft;     -   said housing with said part of said shaft defining a chamber;         and     -   an effective amount of an explosive within said chamber         connectable to detonator means to effect detonation of said         explosive to effect deformation of said housing as to provide         frictional ground retention of said shaft within said ground.

By the term deformation of the housing in this specification and claims is meant that the sides of the housing are deformed in whole or in part, with or without partial break-up or fragmentation of the sides into a plurality of finger or claw like portions, as to provide frictional abutment with or are embedded within the ground constituting the sides of the borehole.

The present invention provides an explosive anchor assembly that uses the energy generated by a small charge of explosive located inside a metal housing to expand or burst the housing to create a friction anchor between the metal and the ground or earth material. The metal expands in whole or in part until an intimate contact between the ground or earth material and the metal is achieved.

The anchor assembly as hereinabove defined may be used in above and below ground situations, e.g. for tying down structures, such as towers, buildings or the like, as well as in mine shafts, tunnels below ground or within mountains as providing shaft, rod or thick wire members retained in the walls, face, roof or floor of a tunnel.

In one aspect, the invention provides an assembly as hereinabove defined wherein the effective amount of the explosive is sufficient to effect deformation of the housing intermittent of the length of the housing at intermittent portions of the housing to effect penetration of the intermittent housing portions into the ground as to be in frictional engagement with the ground.

In another aspect of the invention the effective amount of the explosive is sufficient to effect deformation of the housing along the length of the housing without disintegration thereof to effect frictional abutment of the deformed housing with the ground.

In a further aspect, the effective amount of the explosive is sufficient to effect partial disintegration of the housing as to produce a plurality of housing protrusions penetrated within the ground.

The housing protrusions may penetrate the ground or earth material thickness around the borehole to a desired thickness as determined by the skilled person dependent, inter alia, for example, on the strata and nature of the ground. A typical thickness is selected from 3-15 cm.

In a further aspect, the invention provides a system comprising an object restrained by an object anchor means to or within the ground comprising:

-   -   the object;     -   an elongate anchor;     -   means for connecting the anchor to the object; and     -   ground retaining means for retaining the anchor within the         ground;     -   the improvement comprising the anchor ground retaining means         comprising a deformed housing in frictional ground retention and         attached to the anchor.

In preferred embodiments, the housing is connected to the anchor by complimentary threaded means, such as by nuts and bolts.

The ground entering terminal portion of the elongate anchor is preferably tapered to facilitate ease of entry.

In alternative embodiments, the explosive-loaded assembly may be disposed within a pre-drilled borehole.

In a yet further aspect, the invention provides a method of constructing a system comprising an object restrained to the ground with restraining anchor means comprising an elongate anchor disposed within the ground and attachment means attaching the anchor to the object; the method comprising the steps of locating the anchor within a borehole in the ground and attaching the anchor to the object;

-   -   the improvement comprising     -   (i) connecting at least a portion of the elongate anchor with a         housing, wherein the housing and the anchor define an explosive         containing chamber;     -   (ii) providing the explosive with detonator means; and     -   (iii) detonating the explosive to deform the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be better understood, preferred embodiments will now be described by way of example only, with reference to the accompanying drawings, wherein.

FIG. 1 is a diagrammatic vertical cross-section of an explosive-loaded anchor assembly according to the invention, within a borehold, prior to detonation;

FIGS. 2-4 are diagrammatic vertical cross-sections of various exploded assemblies according to the invention exemplified by FIG. 1 after detonation; and wherein the same numerals denote like parts.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to FIG. 1, this shows generally as 10 an assembly according to the invention having a steel anchor rod 12 encased in a tubular steel housing 14 containing explosive 16. Assembly 12 is located within a suitably sized borehole 18 within the ground 20.

In more detail, housing 14 at its lower terminal portion 22 is tapered and also defines an inner threaded nut portion 24 to receive a complimentary threaded bolt portion 26 of rod 12 which protrudes through nut portion 24 as to facilitate entry into the bottom 28 of borehole 18, if desired.

An upper portion 30 of rod 12 is in suitable close fitting engagement with the neck portion 32 of housing 14. Thus, housing 14 and rod 12 define therebetween a chamber 34 within which is containing a desired type and amount of explosive which is preferably located intermittent of the vertical length of housing 14 and rod 12, as desired, as hereafter further explained.

Anchor rod 12 is of sufficient length to extend beyond the borehole, if desired, and has retaining shackle means 35 by which the anchor holds a guy wire 36 which ties down the tower structure 38 to be held down.

The dimensions of the rod 12, housing 14, amount and type of explosive 16, borehold 18 size are readily selected dependent on the nature of the ground, earth, strata and the like and the holding power required.

The explosive 16 may be located the full length of housing 14 or intermittent therein as shown in the embodiment of FIG. 1. Housing 14 is provided with detonation means (not shown) to effect initiation of explosive 16 in operation when assembly 10 is suitably placed in borehole 18.

With reference to FIG. 2, this shows generally as 50 the result of detonation of an assembly of FIG. 1 wherein the explosive was disposed intermittently along the vertical length of housing 14 in chamber 34 in an amount to propel portions of housing unevenly into the surrounding ground 52 to provide severe deformation without break-up of the shell or skin 14, while providing effective frictional and ingress abutment with the surrounding grounds by portions 54.

FIG. 3 shows generally as 60 the result of detonation of an assembly of FIG. 1 wherein explosive 16 was disposed essentially evenly along the length of housing 14 within chamber 34 in an amount sufficient to propel shell or skin 14 deformed evenly into frictional abutment with the sides of borehole 18.

FIG. 4 shows generally as 70 the result of detonation of an assembly of FIG. 1 wherein explosive 16 is disposed intermittently along housing 14 within chamber 34 in a sufficient amount to effect intermittent break-up of shell 14 into fragments 72 which dig into the surrounding borehole 74 sides 76, while still constituting parts of housing 14 providing an essentially cylindrically disposed plurality of claw members 72. It will be appreciated that full disintegration of the housing must be avoided in order to maintain an integral housing structure connected to rod 12.

The aforesaid embodiments have been described with reference to the anchor assembly being placed in a vertical borehole. However, it will be understood that the assembly may be placed at an angle with respect to the ground, as is known in the art.

Fragments 72 may be desirably operably produced to penetrate to a depth of, typically 5-8 cm, 15 cm or greater by judicious selection of housing dimensions and amount and type of explosive, disposition with respect to the nature of the ground.

As known in the prior art, anchor rods/shafts may be provided in modular form suitably adapted to be joined one shaft to another in 1m, 2m or 3m sections to give a desired total suitable length for use within the borehole. Thus, several assemblies according to the present invention, may be extended into a single joined shaft having suitably located explosive-loaded housings intermittent or full length of the assembled shaft within the ground.

The assemblies according to the invention may be selectively used in all types of ground, such as, for example, limestone strata, granite, Canadian Shield strata, soft soils, sands and permafrost.

A major intention of the practise of the invention defined herein is to try and maintain the integrity of the ground surrounding the borehole and to not disrupt the majority of the annular sides around the resultant positioned anchor, with the minimum of breakaway of the sides of the ground.

Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated. 

1. A ground anchor retaining means assembly for providing a ground-retained anchor retaining means to restrain an object connected thereto, said assembly adapted to be received within a borehole within said ground and comprising an anchor elongate shaft; a housing connected to said shaft and surrounding at least a part of said anchor shaft; said housing with said part of said shaft defining a chamber; and an effective amount of an explosive within said chamber connectable to detonator means to effect detonation of said explosive to effect deformation of said housing as to provide frictional ground retention of said housing within said ground.
 2. A ground anchor assembly as defined in claim 1 of use in providing a ground-retained anchor for use with guy means to restrain a vertical structure, said assembly adapted to be received within a borehole within said ground and comprising an anchor shaft; a housing connected to said shaft and surrounding at least part of said anchor shaft; said housing with said part of said shaft defining a chamber; and an effective amount of an explosive within said chamber connectable to detonator means to effect detonation of said explosive to effect deformation of said housing as to provide frictional ground retention of said housing within said ground.
 3. An assembly as defined in claim 1 wherein said effective amount of said explosive is sufficient to effect deformation of said housing intermittent of the length of said housing at intermittent portions of said housing to effect penetration of said intermittent housing portions into said ground as to be in frictional engagement with said ground.
 4. An assembly as defined in claim 1, wherein said effective amount of said explosive is sufficient to effect deformation of said housing along the length of said housing, without disintegration thereof, to effect frictional abutment of said deformed housing with said ground.
 5. An assembly as defined in claim 1, wherein said effective amount of said explosive is sufficient to effect partial disintegration of said housing as to produce a plurality of housing protrusions penetrated within said ground.
 6. An assembly as defined in claim 5 wherein said housing protrusions are penetratable to a ground thickness selected from 3-15 cm.
 7. A system comprising an object restrained by an object anchor means to or within the ground comprising: said object; an elongate anchor; means for connecting said anchor to said object; and ground retaining means for retaining said anchor within said ground; the improvement comprising said anchor ground retaining means comprising a deformed housing in frictional ground retention and attached to said anchor.
 8. A system as defined in claim 7 wherein said deformed housing comprises partially disintegrated portions.
 9. A system as defined in claim 7 wherein said deformed housing is in fully integral form.
 10. An assembly as defined in claim 1 wherein said elongate anchor has a tapered ground-entering terminal portion.
 11. As system as defined in claim 7 wherein said elongate anchor has a tapered ground-entering terminal portion.
 12. An assembly as defined in claim 1 wherein said housing is connected to said anchor by complimenting threaded means.
 13. A system as defined in claim 7 wherein said housing is connected to said anchor by complimenting threaded means.
 14. A system as defined in claim 11 wherein said terminal portion comprises a threaded portion received by a complimentary threaded portion of said housing.
 15. An assembly as defined in claim 1 wherein said housing is formed of steel.
 16. An assembly as defined in claim 1 wherein said object anchor means comprises a guy wire, strut or like member.
 17. A system as defined in claim 7 wherein said object anchor means comprises a guy wire, strut or like member.
 18. An assembly as defined in claim 1 wherein said object is an above ground structure.
 19. An assembly as defined in claim 1 wherein said object is present within a mine or other subterranean location.
 20. A method of constructing a system comprising an object restrained to the ground with restraining anchor means comprising an elongate anchor disposed within said ground and attachment means attached to said anchor and said object; said method comprising the steps of locating said anchor within a borehole in the ground and attaching said anchor to said object; the improvement comprising (i) providing at least a portion of said elongate anchor with a housing, wherein said housing and said at least a portion of said anchor define an explosive-receiving chamber; (ii) providing said explosive with detonator means; (iii) providing said chamber with an effective amount of said explosive; and (iv) detonating said explosive to deform said housing as to provide frictional ground retention of said housing within said ground.
 21. A method as defined in claim 20 wherein said effective amount of said explosive is sufficient to effect deformation of said housing intermittent of the length of said housing at intermittent portions of said housing to effect penetration of said intermittent housing portions into said ground as to be in frictional engagement with said ground.
 22. A method as defined in claim 20 wherein said effective amount of said explosive is sufficient to effect deformation of said housing along the length of said housing, without disintegration thereof, to effect frictional abutment of said deformed housing with said ground. 